Polyolefins such as a propylene homopolymer and a copolymer of propylene and an α-olefin are each excellent in mechanical physical properties, heat resistance, chemical resistance, water resistance, and the like, are each inexpensive, and therefore have traditionally been used in a wide range of fields such as those of automobile parts and home appliances.
It is known that, the surface of a base material comprising a polyolefin generally has low adhesiveness for materials other than polyolefins and tends to avoid formation of a coated film of an adhesive, a paint, or the like. An attempt has been made to improve painting property and adhesiveness by using modified polyolefins such as a chlorinated polyolefin, an acid-modified chlorinated polyolefin, and an acid-modified polyolefin each as a component of a primer or an adhesive. For the primer and the adhesive, the modified polyolefin is usually used in the form of a solution in an organic solvent or a dispersion in an aqueous solvent and is advantageously used in the form of an aqueous dispersion based on the safety and the environmental viewpoint.
On the other hand, for the primer, the adhesive, and the like each comprising the dispersion of the modified polyolefin, dispersions have been proposed that each use an acrylic resin, a urethane resin, or the like together with the modified polyolefin, to improve adhesiveness for a base material, a paint, and the like each made of a material other than a polyolefin while most of the dispersions concurrently use a curing agent to improve water resistance, solvent resistance, and chemical resistance (Patent Documents 1 to 3).
When the curing agent is concurrently used, problems however arise such as pot life and complication of production steps. A primer and an adhesive are therefore demanded that each are excellent in the coated film properties such as the water resistance, solvent resistance, and chemical resistance without using any curing agent. A primer and an adhesive are also demanded that each do not comprise any halogen substances such as chlorine from the viewpoint of the environmental problems, and polyolefins each modified by chlorine or a material comprising chlorine tend to be skirted.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2013-100399
Patent Document 2: Japanese Patent Publication No. 5071750
Patent Document 3: Japanese Patent Publication No. 5541553